Method of making metal bodies consisting of a core and a shell



Patented Aug. El, 3936 S If ear

essence or trauma METAL BODEES con sis'rnvo or a cone sun A. seam.

Karel Marinas van Gessei and Wilhelmus Daniel van was, Eindhoven, Netherlands, assigncrs to Radio Corporation oi America, a corporation.

or? llielaware.

No Drawing.

This metal bodies no said core body, so that the body thus obtained may be drawn out and rolled.

We have found that this method permits or obtaining excellent results, particularly when starting from a core having a thickness not exceeding ilk-113G in fact it has been found that when using a core having such a thickness 9. wire or plate may be obtained by drawing or rolling in which the core is no longer present per se, this wire or plate practically consisting of pure irconlum. It is also possible to establish bodies comprising a zirconium shell, obtained with the method above referred to, by drawing or rolling it. However, it' has been found that dimculties are sometimes encountered when startingfrom a thicker core for working a body obtained by precipitating zirconium or one of the other metals of the first sub group of the fourth principal group on this core. Due to said difficulties a sheathed wire consisting of a core and of a shell of one of said metals, cannot easily be obtained in this manner. In fact, it has been found that when precipitating the metal on thick cores it is often di'mcult to produce a homogeneous coherent layerl As a result rupture may occur during the drawing or rolling operation so that finally the wire thus obtained may show spots at which the shell material has completely disappeared.

Furthermore, this method has the drawback that it cannot be used with core materials havin a lower melting point than the decomposition temperature of the zirconium compound used.

We now have invented a method by means of which such bodies may be established in a very easy and efhcient manner. This method for producing a body comprising a. core and a shell consisting of one of the metals of the first sub group of the fourth principal group, according to the present invention, consists in that a core body mechanically surrounded by a layer of coherent metal, whereupon the body thus produced is drawn out and/ or rolled. It has been found that Application August 23, 1932, Serial in the Netherlands September ll,

.. @iairns. (cl. Ell -188i in this manner sheathed wires may be obtained having a perfectly uniform and well adhering shell. This method may be advantageously used for zirconium, which metal is provided,- for instance, in the form of thin sheets around the core. which sheets may be obtained by chemically coating a zirconium core with zirconium and by rolling the body thus produced so as to form a thin layer. By surrounding mechanically" is also to be understood in this case the folding or wrapping of such a sheet-shaped piece of air-- conium about the core body.

In many cases it has been found to be very advantageous, to provide the metal with a protesting shell when working it. .By using such a shell the operation is highly facilitated, and,

moreover, the metal of the first sub group of the fourth principal group is protected thereby from atmospheric influences. Such an auxiliary shell may be removed either chemically or mechanically after the operation. As a very suitable material, iron may be used for this purpose. Such a shell may be easily removed by means of hydrochloric acid. For this purpose it is also advantageous to use nickel, which material may be removed with the aid of a small quantity of nitric acid after the operation.

It is observed that the core body need not necessarily consist of a sole material, since this core may also consist, for instance, either of an alloy or consist itself of a sheathed body...

The method may be successfully carried into effect when using a core consisting entirely or partly of molybdenum. Furthermore, nickel has also proved to be a suitable material for this purpose.

The body established by means of the method according to the invention, odors many advantages, so that it may be used for a. great number of applications. Among the advantages first of all, the fact is mentioned that such a body in the form of a sheathed wire has great rigidity so that such a wire may be used instead of pure zirconium wires, thus avoiding the drawback inhercut to the use of the last mentioned wires, viz. their small rigidity. In addition, such sheathed wires are materially cheaper than wires consisting of pure zirconium. Furthermore, the drawback inherent to wires or bodies consisting of pure zirconium, viz. large deformationsoccurring at temperatures of about 1,000 and upwards, is avoided when using bodies made according to the invention. In addition, these wires have the advantages generally inherent to zirconium, ow

ing to which they may be widely used in electron discharge tubes.

As examples of the last mentioned application, zirconium sheathed wires produced according to the method herein described, may be used as grid wires, or when using wire anodes, as anode wires. Such electrodes have the advantage that they are firmer than wire electrodes, consisting of pure zirconium, and are possessed of the property of absorbing occluded gases during operation of the tube, and subject to negligible secondary electron emission. Furthermore, such electrodes will not be subject to deformation at high temperatures.

The invention will be more clearly understood by reference toan example which proves also the simplicity of the method referred to above.

By way of example, we started from a molybdenum or nickel rod having a length of 1 m. and a thickness of 4 mm., which is covered with a zirconium strip having a length of 1 m., a width of 13 mm. and a thickness of 20011., which strip is heated and folded about the rod. After having been cooled down the rod is hammered so that the zirconium surrounds the rod as a tube having a longitudinal seam. 0n the.rod thus obtained is slipped an auxiliary sheath consist: ing, for instance, of iron or nickel, and having usually the shape of a tube. The body thus established is drawn out and rolled in a manner which is well known in the production of sheathed wires and sheathed bands, which operation may be effected at room temperature when using nickel as core material. After this operation the outermost iron shell is "removed, for instance, by dissolving it in hydrochloric acid.

'In this manner may be obtained a zirconium sheathed wire having, for instance, a thickness of In this example of carrying out the invention, reference is made to zirconium sheathed wires,

but it will be appreciated that the invention contemplates application to all bodies comprising a core body and a shell consisting of one of the metals of the first sub group of the fourth prinwith a protective shell, then drawing down thewire thus mechanically coated to suitable size,

and finally removing the said outer protective shell.

2. The method of producing a composite wire comprising a core member and an outer shell which consists in mechanically coating the core with zirconium in the form of a thin metal sheet which is folded about the core and applied in direct contact with the surface thereof, surrounding the zirconium sheet with a protective shell, and then without the application of heatdrawing down the wire thus mechanically coated, and finally removing the said outer protective shell.

KAREL MARINUS VAN GESSEL. WILI-IELMUS DANIEL VAN WIJK. 

